28 HISTORY OF ELECTRICITY. 



a conductor is brought nearer and nearer to an 

 electrized body, the opposite electricity is more and 

 more accumulated by attraction on the side next 

 to the electrized body ; its tension becomes greater 

 by the increase of its quantity and the diminution 

 of the distance, and at kst it is too strong to be 

 contained, and leaps out in the form of a spark. 



The light, sound, and mechanical effects pro- 

 duced by the electric discharge, made the electric 

 fluid to be not merely considered as a mathematical 

 hypothesis, useful for reducing phenomena to for- 

 mulae, (as for a long time the magnetic fluid was,) but 

 caused it to be at once and universally accepted as 

 a physical reality, of which we learn the existence 

 by the common use of the senses, and of which 

 measures and calculations are only wanted to teach 

 us the laws. 



The applications of the theory of electricity 

 which I have principally considered above, are 

 those which belong to conductors, in which the 

 electric fluid is perfectly moveable, and can take 

 that distribution which the forces require. In non- 

 conducting or electric bodies, the conditions to 

 which the fluid is subject are less easy to deter- 

 mine; but by supposing that the fluid moves with 

 great difficulty among the particles of such bodies, 

 that nevertheless it may be dislodged and accu- 

 mulated in parts of the surface of such bodies, by 

 friction and other modes of excitement, and that 

 the earth is an inexhaustible reservoir of electric 



